176 THE GEOGRAPHY OF PLANTS. 



forms seen below the limit of perpetual snow, 

 either in altitude or latitude. They will grow 

 almost everywhere where they can obtain 

 moisture, even on rocks, trees, or the barest 

 ground. 2,400 species are known, and no 

 plants are more widely diffused. Some pro- 

 duce brilliant dyes red, orange, and brown j 

 and one, (Gyropliom^) the " tripe de roche" of 

 arctic travellers, is employed in these regions 

 as a miserable substitute for food. Mosses, 

 too, accompany lichens all over the world, 

 but especially in temperate climes ; and out of 

 1,100 known species, a great part inhabit this 

 zone, and constitute a large portion of the 

 vegetation. A number of flowering plants, 

 some of pretty and elegant forms, many of 

 which are the same as those which grow on 

 the alpine heights of England, Scotland, and 

 middle Europe, here grow in the meadows and 

 down to the sea level. They are chiefly of 

 very low growth and large flowers. Agricul- 

 ture is not altogether stopped, for, in the Scan- 

 dinavian peninsula, barley and rye are 

 cultivated ; barley as high as 70 ; rye, on 

 the western side, to 64, on the eastern to 65 

 or 66. The dry and barren fields are covered 

 with incredible quantities of lichens, among 

 which the rein-deer moss (Cladonia rangiferina) 

 covers the most extensive surfaces with a 

 matting, over which it is very fatiguing to travel 

 in summer, when the plants are dried up by 

 the perpetual sunshine. 



In the elevated regions of Lapland, the trees 



